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Dive into glide reflections, rotations, and more. Practice with real-world examples and graphical representations.
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Five-Minute Check (over Lesson 9–3) CCSS Then/Now New Vocabulary Key Concept: Glide Reflection Example 1: Graph a Glide Reflection Theorem 9.1: Composition of Isometries Example 2: Graph Other Compositions of Isometries Theorem 9.2: Reflections in Parallel Lines Theorem 9.3: Reflections in Intersecting Lines Example 3: Reflect a Figure in Two Lines Example 4: Real-World Example: Describe Transformations Concept Summary: Compositions of Translations Lesson Menu
The coordinates of quadrilateral ABCD before and after a rotation about the origin are shown in the table. Find the angle of rotation. A. 90° clockwise B. 90° counterclockwise C. 60° clockwise D. 45° clockwise 5-Minute Check 1
The coordinates of triangle XYZ before and after a rotation about the origin are shown in the table. Find the angle of rotation. A. 180° clockwise B. 270° clockwise C. 90° clockwise D. 90° counterclockwise 5-Minute Check 2
A.B. C.D. Draw the image of ABCD under a 180° clockwise rotation about the origin. 5-Minute Check 3
The point (–2, 4) was rotated about the origin so that its new coordinates are (–4, –2). What was the angle of rotation? A. 180° clockwise B. 120° counterclockwise C. 90° counterclockwise D. 60° counterclockwise 5-Minute Check 4
Content Standards G.CO.2 Represent transformations in the plane using, e.g., transparencies and geometry software; describe transformations as functions that take points in the plane as inputs and give other points as outputs. Compare transformations that preserve distance and angle to those that do not (e.g., translation versus horizontal stretch). G.CO.5 Given a geometric figure and a rotation, reflection, or translation, draw the transformed figure using, e.g., graph paper, tracing paper, or geometry software. Specify a sequence of transformations that will carry a given figure onto another. Mathematical Practices 1 Make sense of problems and persevere in solving them. 4 Model with mathematics. CCSS
You drew reflections, translations, and rotations. • Draw glide reflections and other compositions of isometries in the coordinate plane. • Draw compositions of reflections in parallel and intersecting lines. Then/Now
composition of transformations • glide reflection Vocabulary
Graph a Glide Reflection Quadrilateral BGTS has vertices B(–3, 4), G(–1, 3), T(–1 , 1), and S(–4, 2). Graph BGTS and its image after a translation along 5, 0 and a reflection in the x-axis. Example 1
Graph a Glide Reflection Step 1 translation along 5, 0 (x, y) →(x + 5, y) B(–3, 4)→ B'(2, 4) G(–1, 3)→ G'(4, 3) S(–4, 2)→ S'(1, 2) T(–1, 1)→ T'(4, 1) Example 1
Graph a Glide Reflection Step 2 reflection in the x-axis (x, y)→(x, –y) B'(2, 4)→ B''(2, –4) G'(4, 3)→ G''(4, –3) S'(1, 2)→ S''(1, –2) T'(4, 1)→ T''(4, –1) Answer: Example 1
Quadrilateral RSTU has vertices R(1, –1), S(4, –2), T(3, –4), and U(1, –3). Graph RSTU and its image after a translation along –4, 1and a reflection in the x-axis. Which point is located at (–3, 0)? A.R' B.S' C.T' D.U' Example 1
Graph Other Compositions of Isometries ΔTUV has vertices T(2, –1), U(5, –2), and V(3, –4). Graph ΔTUV and its image after a translation along –1 , 5 and a rotation 180° about the origin. Example 2
Graph Other Compositions of Isometries Step 1 translation along –1 , 5 (x, y) →(x + (–1), y + 5) T(2, –1)→ T'(1, 4) U(5, –2)→ U'(4, 3) V(3, –4)→ V'(2, 1) Example 2
Graph Other Compositions of Isometries Step 2 rotation 180 about the origin (x, y)→(–x, –y) T'(1, 4)→ T''(–1, –4) U'(4, 3)→ U''(–4, –3) V'(2, 1)→ V''(–2, –1) Answer: Example 2
ΔJKL has vertices J(2, 3), K(5, 2), and L(3, 0). Graph ΔTUV and its image after a translation along 3, 1and a rotation 180° about the origin. What are the new coordinates of L''? A. (–3, –1) B. (–6, –1) C. (1, 6) D. (–1, –6) Example 2
Reflect a Figure in Two Lines Copy and reflect figure EFGH in line p and then line q. Then describe a single transformation that maps EFGH onto E''F''G''H''. Example 3
Reflect a Figure in Two Lines Step 1 Reflect EFGH in line p. Example 3
Reflect a Figure in Two Lines Step 2 Reflect E'F'G'H' in line q. Answer: EFGH is transformed onto E''F''G''H'' by a translation down a distance that is twice the distance between lines p and q. Example 3
Copy and reflect figure ABC in line s and then line t. Then describe a single transformation that maps ABC onto A''B''C''. A.ABC is reflected across lines and translated down 2 inches. B.ABC is translated down 2 inches onto A''B''C''. C.ABC is translated down 2 inches and reflected across line t. D.ABC is translated down 4 inches onto A''B''C''. Example 3
Describe Transformations A. LANDSCAPING Describe the transformations that are combined to create the brick pattern shown. Example 4
Describe Transformations Step 1 A brick is copied and translated to the right one brick length. Example 4
Describe Transformations Step 2 The brick is then rotated 90°counterclockwise about point M, given here. Example 4
Describe Transformations Step 3 The new brick is in place. Answer: The pattern is created by successive translations and rotations shown above. Example 4
Describe Transformations B. LANDSCAPING Describe the transformations that are combined to create the brick pattern shown. Example 4
Describe Transformations Step 1 Two bricks are copied and translated 1 brick length to the right. Example 4
Describe Transformations Step 2 The two bricks are then rotated 90 clockwise or counterclockwise about point M, given here. Example 4
Describe Transformations Step 3 The new bricks are in place. Another transformation is possible. Example 4
Describe Transformations Step 1 Two bricks are copied and rotated 90 clockwise about point M. Example 4
Describe Transformations Step 2 The new bricks are in place. Answer: The pattern is created by successive rotations of two bricks or by alternating translations then rotations. Example 4
A.What transformation must occur to the brick at point M to further complete the pattern shown here? A. The brick must be rotated 180° counterclockwise about point M. B. The brick must be translated one brick width right of point M. C. The brick must be rotated 90° counterclockwise about point M. D. The brick must be rotated 360° counterclockwise about point M. Example 4
B.What transformation must occur to the brick at point M to further complete the pattern shown here? A. The two bricks must be translated one brick length to the right of point M. B. The two bricks must be translated one brick length down from point M. C. The two bricks must be rotated 180° counterclockwise about point M. D. The two bricks must be rotated 90° counterclockwise about point M. Example 4